Navigation device and method for displaying alternative routes

ABSTRACT

A navigation device has a route re-calculation function. This is activated by the user touching the screen to task away from the normal navigation map mode to a menu screen which displays multiple types of route re-calculation options.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates to a navigation device that can displaynavigation data. The device find particular application as an in-carnavigation system.

2. Description of the Prior Art

GPS based devices are well known and are widely employed as in-carnavigation systems. Reference may be made to the Navigator seriessoftware from the present assignee, TomTom B.V. This is software that,when running on a PDA (such as a Compaq iPaq) connected to an externalGPS receiver, enables a user to input to the PDA a start and destinationaddress. The software then calculates the best route between the twoend-points and displays instructions on how to navigate that route. Byusing the positional information derived from the GPS receiver, thesoftware can determine at regular intervals the position of the PDA(typically mounted on the dashboard of a vehicle) and can display thecurrent position of the vehicle on a map and display (and speak)appropriate navigation instructions (e.g. ‘turn left in 100 m’).Graphics depicting the actions to be accomplished (e.g. a left arrowindicating a left turn ahead) can be displayed in a status bar and alsobe superimposed over the applicable junction's/turnings etc in the roadsshown in the map itself. Reference may also be made to devices thatintegrate a GPS receiver into a computing device programmed with a mapdatabase and that can generate navigation instructions on a display. Theterm ‘navigation device’ refers to a device that enables a user tonavigate to a pre-defined destination. The device may have an internalsystem for receiving location data, such as a GPS receiver, or maymerely be connectable to a receiver that can receive location data.

It is known to enable in-car navigation systems to allow the driver,whilst driving in a car along a route calculated by the navigationsystem, to initiate a route re-calculation. This is useful where thevehicle is faced with construction work or heavy congestion. Referencemay be made to U.S. Pat. No. 6,118,389 which discloses techniques forcalculating a re-route. Initiating the re-route calculation requiresactivation of a specific detour switch, which may however beinconvenient to the user. Reference may also be made to U.S. Pat. No.5,544,060, which enables a device to preview the calculated route bydisplaying in successive screens each different road and turning thatthe vehicle has to take; the user however has to manually sequencethrough each successive screen using a preview switch until he reachesthe road that he wants to exclude from the route; he then selects acancel switch; a new route is calculated which excludes the cancelledroad.

The present invention aims to improve on the user interaction aspects ofinitiating a route recalculation.

SUMMARY OF THE INVENTION

In a first aspect, there is a navigation device programmed with a mapdatabase and software that enables a route to be planned between twouser-defined places, wherein the device is further programmed to be ableto display a navigation map on a touch screen display, the map updatingthe current position of the device; wherein the user can, by touchingthe screen, task away from the navigation map to a menu screen whichdisplays one or more options that, if selected through a further touchaction, initiate a re-calculation of the route.

This user interaction approach is simpler, more flexible and moreintuitive than prior art approaches that require the user to activate aspecific, hardware-based detour switch. Further, since a routere-calculation only requires 2 quick touch actions to the screen, it canbe safely completed by a driver even whilst driving.

The menu screen may displays selectable options relating to one or moreof the following functions:

-   -   (a) calculate alternative route;    -   (b) calculate alternative route without including a predefined        extend of the road ahead;    -   (c) calculate alternative route without including a predefined        road;    -   (d) revert to original route.

This approach gives the driver far greater flexibility in his routere-calculation options than was available with prior art, hard-wireddetour switches.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will be described with reference to theaccompanying drawings, in which

FIG. 1 is a screen shot from a navigation device implementing thepresent invention; the screen shot shows a plan map view and a statusbar running along the bottom of the display;

FIG. 2 is a screen shot from the navigation device implementing a 3-Dview;

FIG. 3 is a screen shot from the navigation device showing various routeplanning functions that enable a user to require the device to plot anew route to the destination that (i) is an alternative route; (ii)avoids a roadblock immediately ahead; (iii) avoids predefined roads or(iv) is a reversion to the original route.

DETAILED DESCRIPTION

System Overview

The present invention is implemented in software from TomTom B.V. calledNavigator. Navigator software runs on a touch screen (i.e. styluscontrolled) Pocket PC powered PDA device, such as the Compaq iPaq. Itprovides a GPS based navigation system when the PDA is coupled with aGPS receiver. The combined PDA and GPS receiver system is designed to beused as an in-vehicle navigation system. The invention may also beimplemented in any other arrangement of navigation device, such as onewith an integral GPS receiver/computer/display, or a device designed fornon-vehicle use (e.g. for walkers) or vehicles other than cars (e.g.aircraft). The navigation device may implement any kind of positionsensing technology and is not limited to GPS; it can hence beimplemented using other kinds of GNSS (global navigation satellitesystem) such as the European Galileo system. Equally, it is not limitedto satellite based location/velocity systems but can equally be deployedusing ground-based beacons or any other kind of system that enables thedevice to determine its geographic location.

Navigator software, when running on a PDA, results in a navigationdevice that causes the normal navigation mode screen shown in FIG. 1 tobe displayed. This view provides driving instructions using acombination of text, symbols, voice guidance and a moving map. Key userinterface elements are the following: a 2-D map 1 occupies most of thescreen. The map shows the user's car and its immediate surroundings,rotated in such a way that the direction in which the car is moving isalways “up”. Running across the bottom quarter of the screen is thestatus bar 2. The current location of the device, as the device itselfdetermines using conventional GPS location finding and its orientation(as inferred from its direction of travel) is depicted by an arrow 3.The route calculated by the device (using route calculation algorithmsstored in device memory as applied to map data stored in a map databasein device memory) is shown as darkened path 4 superimposed with arrowsgiving the travel direction. On the darkened path 4, all major actions(e.g. turning corners, crossroads, roundabouts etc.) are schematicallydepicted by arrows 5 overlaying the path 4. The status bar 2 alsoincludes at its left hand side a schematic 6 depicting the next action(here, a right turn). The status bar 2 also shows the distance to thenext action (i.e. the right turn—here the distance is 220 meters) asextracted from a database of the entire route calculated by the device(i.e. a list of all roads and related actions defining the route to betaken). Status bar 2 also shows the name of the current road 8, theestimated time before arrival 9 (here 2 minutes and 40 seconds), theactual estimated arrival time 10 (11.36 am) and the distance to thedestination 11 (1.4 Km). The GPS signal strength is shown in amobile-phone style signal strength indicator 12.

If the user touches the centre of the screen 13, then a navigationscreen menu is displayed; from this menu, other core navigationfunctions within the Navigator application can be initiated orcontrolled. Allowing core navigation functions to be selected from amenu screen that is itself very readily called up (e.g. one step awayfrom the map display to the menu screen) greatly simplifies the userinteraction and makes it faster and easier.

The area of the touch zone which needs to be touched by a user is farlarger than in most stylus based touch screen systems. It is designed tobe large enough to be reliably selected by a single finger withoutspecial accuracy; i.e. to mimic the real-life conditions for a driverwhen controlling a vehicle; he or she will have little time to look at ahighly detailed screen with small control icons, and still less time toaccurately press one of those small control icons. Hence, using a verylarge touch screen area associated with a given soft key (or hidden softkey, as in the centre of the screen 13) is a deliberate design featureof this implementation. Unlike other stylus based applications, thisdesign feature is consistently deployed throughout Navigator to selectcore functions that are likely to be needed by a driver whilst actuallydriving. Hence, whenever the user is given the choice of selectingon-screen icons (e.g. control icons, or keys of a virtual keyboard toenter a destination address, for example), then the design of thoseicons/keys is kept simple and the associated touch screen zones isexpanded to such a size that each icon/key can unambiguously be fingerselected. In practice, the associated touch screen zone will be of theorder of at least 0.7 cm² and will typically be a square zone. In normalnavigation mode, the device displays a map. Touching the map (i.e. thetouch sensitive display) once (or twice in a different implementation)near to the screen centre (or any part of the screen in anotherimplementation) will then call up a navigation menu (see FIG. 3) withlarge icons corresponding to various navigation functions, such as theoption to calculate an alternative route, and re-calculate the route soas to avoid the next section of road (useful when faced with anobstruction or heavy congestion); or recalculate the route so as toavoid specific, listed roads.

The actual physical structure of the device itself may be fundamentallyno different from any conventional handheld computer, other than theintegral GPS receiver or a GPS data feed from an external GPS receiver.Hence, memory stores the route calculation algorithms, map database anduser interface software; a microprocessor interprets and processes userinput (e.g. using a device touch screen to input the start anddestination addresses and all other control inputs) and deploys theroute calculation algorithms to calculate the optimal route. ‘Optimal’may refer to criteria such as shortest time or shortest distance, orsome other user-related factors.

More specifically, the user inputs his start position and requireddestination in the normal manner into the Navigator software running onthe PDA using a virtual keyboard. The user then selects the manner inwhich a travel route is calculated: various modes are offered, such as a‘fast’ mode that calculates the route very rapidly, but the route mightnot be the shortest; a ‘full’ mode that looks at all possible routes andlocates the shortest, but takes longer to calculate etc. Other optionsare possible, with a user defining a route that is scenic—e.g. passesthe most POI (points of interest) marked as views of outstanding beauty,or passes the most POIs of possible interest to children or uses thefewest junctions etc.

Roads themselves are described in the map database that is part ofNavigator (or is otherwise accessed by it) running on the PDA aslines—i.e. vectors (e.g. start point, end point, direction for a road,with an entire road being made up of many hundreds of such sections,each uniquely defined by start point/end point direction parameters). Amap is then a set of such road vectors, plus points of interest (POIs),plus road names, plus other geographic features like park boundaries,river boundaries etc, all of which are defined in terms of vectors. Allmap features (e.g. road vectors, POIs etc.) are defined in a co-ordinatesystem that corresponds or relates to the GPS co-ordinate system,enabling a device's position as determined through a GPS system to belocated onto the relevant road shown in a map.

Route calculation uses complex algorithms that are part of the Navigatorsoftware. The algorithms are applied to score large numbers of potentialdifferent routes. The Navigator software then evaluates them against theuser defined criteria (or device defaults), such as a full mode scan,with scenic route, past museums, and no speed camera. The route whichbest meets the defined criteria is then calculated by a processor in thePDA and then stored in a database in RAM as a sequence of vectors, roadnames and actions to be done at vector end-points (e.g. corresponding topre-determined distances along each road of the route, such as after 100meters, turn left into street x).

Route Re-Calculation

An implementation of the present invention facilitates access tofunctions that enable alternative routes to be calculated by placing amenu of graphical icons (or any other kind of way or option to allowselection of the functions, such as lists, check boxes etc.) on a menuscreen that is easily accessed from the main navigation screen—i.e. thescreen that is displayed during actual or simulated/preview navigation.As noted above, in normal navigation mode (and also the ‘demonstrateroute’ mode for simulated/preview navigation—see later), the devicedisplays an animated map that shows the location of the navigationdevice as the journey progresses. Touching the map (i.e. the touchsensitive display) once (or twice in a different implementation) near tothe screen centre (or any part of the screen in another implementation)will then call up a ‘Recalculate’ menu screen (see FIG. 3) with largeicons corresponding to various navigation functions, such as the optionto calculate an alternative route 3C; re-calculate the route so as toavoid the next section of road 3A (useful when faced with a roadblock);and recalculate the route so as to avoid specific, listed roads 3B. Thefollowing sections describe these and other alternative route functionsin more detail. Some of these functions may be initiated directly fromthe Recalculate menu screen; others may be at a deeper level in the menustructure. However, all can be initiated by selecting options such asgraphical icons, lists, check boxes which are unambiguously associatedwith touch screen areas that are large enough to allow the user toselect them with a fingertip whilst safely driving, typically at least0.7 cm² in area.

Alternative Route Function: ‘Avoid Roadblock’

With this function, a user could select an ‘avoid roadblock’ function 3Athat causes the system to recalculate a route on the basis that the roadimmediately ahead (or some user defined or system default distanceahead, e.g. 100 metres) is blocked.

As noted earlier, a route planning algorithm in Navigator will work outan optimal route (optimal may refer to criteria such as shortest time orshortest distance, or some other factors) by exploring different routesand scoring them against the required criteria. In this way, one routewhich best meets the defied criteria is generated. If whilst actuallydriving along a route, an unexpected event occurs that requires the userto detour away from the pre-calculated route, such as a roadblock, theuser can inform the Navigator software that his immediate road ahead isblocked and require the software to re-calculate a new route, taking hiscurrent position as a new starting position, but taking the firstturning possible away from the old calculated route. This first turningmight be ahead or behind the current car position. The system, inconstructing the new route, explores a large number of possible routesto the destination from the current position, but excludes the roadimmediately ahead.

Selecting the ‘avoid roadblock’ function 3A has to be fast and involvethe absolute minimum number of screen interactions to minimise driverdistraction. This can be achieved by the user being able to switch fromnormal navigation mode (in which the current position of the car isshown on a map, as shown in FIG. 1 or 2) to a Recalculate menu mode, asshown in FIG. 3, by pressing a key or selecting any point on the screenor selecting a given region of the screen. Where a given region has tobe selected (e.g. the approximate centre of the map), then the touchactivation zone is sufficiently large that it can readily and reliablybe selected by a user with his fingertip without needing to lookcarefully at the screen for more than a moment. A touch zone of 0.7 cm²,centred on the map, has been found to be sufficient.

The FIG. 3 menu mode displays a small number of large icons, one ofwhich is the ‘avoid roadblock’ 3A option. This can be selected with onetouch; when this occurs, the software re-calculates the route and givesinstructions in the normal manner (voice; and/or on screen navigationprompts) to allow the user to proceed to his destination but avoid theroad immediately ahead.

Alternative Route Function: ‘Avoid Specific Road’

This function allows a user to easily and rapidly select a specific,named road 3B to mark as blocked so that he can use information fromreal time traffic information broadcasts on the radio.

When listening to the radio, a user may hear that a specific road orperhaps part of a motorway between defined junctions is blocked orheavily congested. If that road is on the user's calculated route, eventhough it might be many kilometres away, then he will want to have thesoftware recalculate a new route as soon as possible. The system doesthis by calculating a route to the final destination using the currentposition as a start position and exploring different routes to thedestination, but excluding the road indicated as to be avoided. The newroute will then be calculated using normal route planning algorithms andthe user diverted onto the new route.

Selecting the ‘avoid specific road’ function 3B has also to be fast andinvolve the absolute minimum number of screen interactions to minimisedriver distraction. This can be achieved by the user being able toswitch from normal navigation mode (FIG. 1 or 2, in which the currentposition of the car is shown on a map) to a Recalculate menu mode asdescribed earlier (e.g. selecting a given region on the screen); theRecalculate menu displays a small number of large icons, several ofwhich are named roads 3B on the route which, if selected, can beselected with one touch; when this occurs, the software re-calculatesthe route and gives instructions in the normal manner (voice; and/or onscreen navigation prompts) to allow the user to proceed to hisdestination but avoid the road immediately ahead. The device may havelimited screen space to display many roads for exclusion; the FIG. 3implementation lists three. These three are selected using variousweighting, parameters (e.g. a prior history of the user wishing to avoidthem; the next three major roads) or from dynamic, updated travelinformation received by the device from a traffic information datasource, indicating that these are the next three roads on the route thatare affected by traffic disturbance of some kind.

A final ‘original’ option 3D allows the user to clear all earlierre-calculation inputs and re-calculate the original route.

A number of other navigation functions can be initiated from deeper inthe menu hierarchy than the FIG. 3 menu. These are described below.

Alternative Route Function: ‘Penalties’

With this function, the system can also enable a user to mark certainpoints/regions as blocked or slow or to give penalties (or theirinverse, awards) to a point/region to weight routing away from (or to)that point/region and have the system auto calculate an alternativeroute (or indeed the original route).

Route planning algorithms operate by assigning scores to differentpossible routes in relation to different criteria (e.g. scores for thetime of journey, scores for the length of journey etc) and thendetermining which route has the best overall score. Normally, the usercannot interact directly with how the algorithm treats roads, junctionsand other route features. But in Navigator it is possible: the user candirectly alter the way the route planning algorithm evaluates or scoresa route by awarding penalties/awards to any items, e.g. points/regions,that affect the route planning scoring. The route planning algorithmstores a list of all roads/junctions in vector form associated with eachcalculated route from start to destination; each item (e.g. roadsection, turning etc.) will typically have several parameters associatedwith it that are used in the scoring process to evaluate a best route.Hence, it is straightforward to alter the route scoring based on givingdifferent weightings to different kinds of items. For example, one usermight dislike junctions; in which case, the route scoring could countjunction numbers in alternate routes and then weight more favourablyroutes with fewer junctions. Similarly, roads within certain userdefined regions could have some of their scoring parameters altered tochange the likelihood of a route being selected using them (either toincrease or decrease the likelihood of selection). To enable the user toalter the weightings given to different items, the device could displaya list of those items adjacent to check boxes (e.g. ‘Like’ and ‘Don'tLike’). Each user could then set up a personal profile that defined hisor her personal preferences (e.g. one person might always prefer thescenic and historic; another straightforward driving with minimaljunctions; yet another, always the shortest possible distance,irrespective of complexity).

Also, a user could penalise specific complex junctions on a simulatedroute (see ‘Demonstrate route’ function below) if they disliked them, orelse could indicate that he wanted fewer turnings and the device wouldthen count the number of turnings in alternative routes and givepreference to the routes with fewer turnings.

Alternative Route Function: Auto Generate

A user can also simply select ‘alternative route’ 3C if he wants to seeanother possible route: the system then recalculates a route, not usingat least 80% of the roads from the prior route. If that route is stillunsuitable, the user can obtain another alternative route again byselecting again ‘alternative route’ 3C.

Alternative Route Planning: Selecting Calculation Modes

A user can select ‘normal’, ‘strict’ and ‘fast’ planning modes: eachresults in different route planning algorithms being used that calculatethe route either normally, or strictly (which may take many minutes as agreat many permutations are explored) or quickly, (which may take a fewseconds only as many simplifying assumptions are made about the optimalroute).

Alternative Route Planning: POI Navigation

The system offers a “navigate to nearby point of interest” option. Thisfirst provides a hot list of POI (point of interest) icons for the smallset of most often used POI types.

The list is initialized to generally useful POI types (for car drivers)like petrol stations, restaurants, parking spots etc. Hence, a user canvery readily ask the program to calculate a new route that will navigatehim to the nearest petrol station etc. This can happen during the courseof a drive—i.e. the user realises that he is low on fuel and will needthe route to be re-calculated to pass by a petrol station, whilst stillmaintaining the original destination.

The system can in effect recalculate a route with the closest relevantPOI as the destination and the current location as the start The usercan manually adjust the types to suit his own needs. Furthermore, atleast one of the icons will self-adjust to the most recently used typenot already in the list.

Re-calculating a route to include a POI requires the system to implementa search for POIs. This would normally be done by defining a point andsearching outwards from that point to locate relevant POIs. Applyingthis approach to finding POIs along a route would be impossible on a PDAbecause you would in effect be replicating the search for all pointsalong the route (potentially millions of separate searches for a longjourney, which would be too great a load). In this implementation, thisapproach is reversed by taking each relevant POI and seeing if it is ona vector/line that that also defines part of the route—a simple and fastcorrelation process between POIs and route lines, that can rapidly berepeated for all POIs of relevance and for each candidate route. ThisPOI location method can be used whenever POIs need to be found. Whenre-calculating a route so that it includes a POI of a given type, theroute calculation algorithm takes as its start position the currentlocation and maintains the original destination. It then selects onlythose routes that include the POI of the required type (using the simplecorrelation process of seeing if any vector of the calculated routematches the vector associated with each POI of the required type) andweights most favourably those with a POI nearest the current location.

Demonstrate Route Function

The present invention implements a ‘Demonstrate route’ preview orsimulation function. This allows the user to see the entire proposedroute, as calculated by the Navigator software, in animated fashion asif he were driving it. First, a route is calculated in the normalmanner. Then, a ‘demonstrate route’ icon or menu option is automaticallydisplayed by the device after the route is calculated. As with all majornavigation functions, this is represented by a large icon with anassociated touch screen area large enough to be readily selected by afingertip, such as at least 0.7 cm². After the icon has been selected,the device displays a sequence of preview maps that shows the cardriving from the start position to the destination. Generally, the mapswill be animated to scroll past a fixed point representing the vehicleposition, although it is possible to arrange for the position of thevehicle to advance as though travelling along a road, or for there to besome combination of relative movement between car and route.

Other useful control functions can mimic the video/media player controlfunctions found on a PC; for example, to fast forward through thesimulation/preview and to pause, play, and rewind. The status bar data(especially time of arrival, further journey time and remainingdistance) should remain accurate as the off-line simulation of the routeplays. This gives the user a good feel for not only the spatialdefinition of the route, but also its temporal definition.

During normal preview (e.g. when a ‘play’ button on a media player stylecontrol is selected), each road name is displayed in the status bar 8.One possible refinement is to only display the road name if it willremain visible for more than a predetermined time (e.g. 1 second).Whilst the preview is fast forwarding, then road names may not bedisplayed if they would not be legible (in less sophisticatedimplementations this feature may be absent). Road names may alsodisplayed if the pause is selected or if the simulated speed of thevehicle is otherwise slowed down below a defined level.

During normal preview, road names are therefore displayed in the statusbar 8 or superimposed over the road itself in the map (whether 2-d or3-D), in the same way that they are displayed during normal real-timeoperation, greatly enhancing the realism and utility of the previewfunction. For example, the ‘demonstrate route’ function is very helpfulin enabling users/passengers to assess and confirm that the route isacceptable. The user can familiarise himself with the road names in thesame context as they will appear on the device when actually driving.For some vehicles, such as taxis, this is especially valuable for thepassenger. It is also very useful for point-of-sale purposes to catchthe eye of potential purchasers of the Navigator software and GPSsystem; hence, at a retail store, replaying a route on a PDA usingNavigator may be desirable.

The user can therefore, with the present invention, ask for the entirejourney along the route to be simulated on a map displayed on thedevice: in the conventional manner, the position of the car on thedisplayed map is marked with an arrow; as the journey simulationprogresses, the streets move past the car arrow, which is optimallyfixed approximately ⅓^(rd) up from the bottom of the map, and centred.The car is hence shown actually navigating along the route calculated bythe Navigator software. In this way, a user can check that the routelooks acceptable; the user may for example, prefer a route that avoids acertain region and he may want to confirm that the route suggested bythe program does bypass it Or the user may simply feel more comfortabledriving a route that he has had fully described and shown to him by thesoftware before hand. In a point of sale system, the simulation cancontinuously repeat.

The animated maps may be in 2-D view (e.g. as shown in FIG. 1) or in3-D, as shown in FIG. 2. 3-D animations (as well as real-time 3-D mapviews) can be altered to change the simulated viewing height; forexample, for aviation use, it may be very useful to be able to show a3-D view of an entire flight route from a simulated height useful to thepilot. This height may vary automatically depending on the height of theplane; in addition, simulated height (as well as other kinds ofperspective alteration) controls can be added as, for example, controlicons on the edge of the screen. The simulated height above groundand/or perspective of the 3-D map can also alter automatically as therate of progress alters—e.g. for very rapid preview (corresponding tovery fast vehicle speed) then the simulated height above ground canincrease to give better visibility.

The demonstrate route function can also be usefully deployed when theuser wishes to have an alternative route calculated by the device andwants that alternative route animated as an off-line simulation orpreview. For example, whilst the simulation is running, the user can, bytouching the screen, task away from the simulation to a menu screen(FIG. 3) which displays one or more options that, if selected through atouch action, initiate a re-calculation of the route. The menu screendisplays icons relating to one or more of the following functions:

-   -   (a) calculate alternative route;    -   (b) calculate alternative route without including a predefined        extent of the road ahead;    -   (c) calculate alternative route without including a predefined        road;

Once a re-calculation has been performed, the device automaticallydisplays an option to initiate a simulation of that recalculated route.

Equally, the preview function can be initiated during actual, realprogress along a calculated route; for example, the user may wish tore-calculate a new route (perhaps finding heavy congestion); he thentouches the screen to task away from the navigation map and then reachesthe menu screen that displays the route re-calculation options (FIG. 3).Once re-calculation is complete, the device automatically displays a‘demonstrate route’ icon. This is particularly useful afterre-calculation during an actual journey as the user may wish to verifythat that the re-calculated route is appropriate (e.g. does not useroads that the user now knows should not be used because of congestionetc.) by viewing the preview/simulation.

1. A navigation device programmed with a map database and software thatenables a route to be planned between two user-defined places, whereinthe device is further programmed to be able to display a navigation mapon a touch screen display, the map updating the current position of thedevice; wherein the user can, by touching the screen, task away from thenavigation map to a menu screen which displays one or more options that,if selected through a further touch action, initiate a re-calculation ofthe route.
 2. The device of claim 1 in which the task away is initiatedby a single or a double touch anywhere on the touch screen.
 3. Thedevice of claim 1 in which the task away is initiated by a single or adouble touch at a region of the touch screen sized to be sufficientlylarge to allow it to be reliably selected with a fingertip.
 4. Thedevice of claim 3 in which the region is centred on the navigation map.5. The device of claim 3 in which the region is at least 0.7 cm² inarea.
 6. The device of claim 1 in which the menu screen displaysselectable options relating to one or more of the following functions:(a) calculate alternative route; (b) calculate alternative route withoutincluding a predefined extent of the road ahead; (c) calculatealternative route without including a predefined road; (d) revert tooriginal route.
 7. The device of claim 1 in which the navigation map isa preview or simulation of a journey along the route and the currentposition is a simulated current position.
 8. The device of claim 1 inwhich each selectable option is one of the following: (a) a graphicalicon; (b) a control or check box; or (c) a name.
 9. The device of claim1 which enables a user to alter the way a route is evaluated or scoredby a route calculation algorithm.
 10. The device of claim 9 in whichenabling the altering of the way a route is evaluate or scored isachieved by allowing the user to alter the weight given to any item usedin the evaluation of a route.
 11. The device of claim 1 in which the mapis a 3-D map.
 12. The device of claim 1 that displays options that allowthe user to initiate different route calculation modes.
 13. The deviceof claim 1 that displays an option to recalculate a route to include aPOI of a user-defined type.
 14. The device of claim 13 in which thedevice correlates vectors of POIs of the defined type to vectors indifferent routes to enable it to select only those routes that includethe required POI.
 15. A method of displaying navigation information, themethod being deployed in a navigation device programmed with a mapdatabase and software that enables a route to be planned between twouser-defined places, wherein the device is further programmed to be ableto display a navigation map on a touch screen display, the map updatingthe current position of the device; characterised in that the user can,by touching the screen, task away from the navigation map to a menuscreen which displays one or more options that, if selected through afurther touch action, initiate a re-calculation of the route. 16.Computer software adapted to enable a navigation device, programmed witha map database and software that enables a route to be planned betweentwo user-defined places and displayed on a navigation map on a touchscreen display, the map updating the current position of the device;wherein the software enables a user, by touching the screen, task awayfrom the navigation map to a menu screen which displays one or moreoptions that, if selected through a further touch action, initiate are-calculation of the route